Microscopes are often used in operating rooms during surgical procedures. During many of these procedures, such as spinal and cranial procedures, the surgeon must manipulate exceptionally small blood vessels, nerve bundles, muscles, nerves and other tissue. These procedures require viewing the surgical site through a surgical microscope so that the fine details in the surgical site can be clearly seen by the surgeon. However, during an operation, the area around the surgical site must remain sterile. A surgical field, as present in a typical hospital's operating room, is an environmentally controlled area where the risk of infection from naturally occurring organisms, such as bacteria, is minimized. The environment's sterility is thus controlled by limiting the introduction of infection-causing bacteria and other contaminants by maintaining strict control over the personnel and equipment present in an operating room.
As it is difficult or impossible to sterilize the surgical microscope, it is common practice to cover the microscope with a sterile drape. The drape typically comprises a flexible tube of sheet-form material that covers all of the components of the surgical microscope, to include the ocular ports of the microscope head and the structure that supports the head. The drape also typically includes a transparent window therein for attachment to the objective lens of the microscope. The drape is typically manufactured and packaged in a sterile condition so that when it is unpackaged in the operating room and placed on a microscope, it creates a sterile field around the microscope and its components.
However, various disadvantages have been realized in trying to adapt sterile drapes to surgical microscopes. One disadvantage arises because many hospitals utilize different configurations of microscopes to perform different types of surgical procedures. Microscopes can be configured to include a variety of ocular view ports in a variety of locations, with such configuration depending on the surgical procedure to be performed. The number and location of ocular ports of a given microscope depends on the surgical procedure taking place and the number of surgeons and or assistants present during the procedure. For example, during cranial operations, surgeons typically stand at the head of the patient side-by-side of one another, with a lead surgeon standing next to one or more assisting surgeons. Thus, with the cranial configuration, the microscope may have up to three ocular ports located approximately side-by-side of one another on one side of the microscope.
This ocular port configuration changes for spinal operations, where surgeons typically stand on opposite sides of a given patient, with a lead surgeon and an assisting surgeon standing preferably 180 degrees from one another on opposite sides of a patient, and up to two assisting surgeons standing on either side of the lead surgeon. With the cranial configuration, the microscope may thus have up to three ocular ports located approximately side-by-side of one another on one side of the microscope and a fourth ocular port located on an opposite side of the microscope, preferably 180 degrees from the lead surgeon's ocular port.
To effectively cover the microscope, it is usually necessary to form the microscope drape with one or more ocular pockets to accommodate the microscope's ocular ports. Prior art drapes have up to three ocular pockets to accommodate the ocular ports of a given microscope. Although such drapes have proven sufficient for use with microscopes configured for cranial operations, with the three ocular pockets accommodating the up to three ocular ports located on one side of a microscope, they prove insufficient during cranial operations requiring the use of four ocular ports. Furthermore, the prior art drapes, having up to three ocular pockets located side-by-side of one another, prove insufficient for use during cranial procedures utilizing as few as two ocular ports, with the two ocular ports used during such procedure being located preferably 180 degrees from one another.
For the prior art drapes to accommodate a microscope having two ocular ports configured for a cranial operation (i.e. located preferably 180 degrees from one another), the ocular pockets of the prior art drape, located side-by-side of one another, must be stretched across the head of the microscope to cover the two opposing ports. Such stretching usually causes tension at some portions of the drape, especially at the joint between the main cover portion and the ocular pockets, thus causing the drape material to deform, rip or rupture. Such a rupture compromises the sterile field established by the drape, requiring a replacement of the drape itself.
Furthermore, in positioning the prior art drapes on the microscope to accommodate the opposing ocular ports, a tearing of the drape may occur around the drape's lens cover, which is typically mounted to the objective lens barrel of the microscope, again compromising the sterile field. Although such tearing may be avoided through a rotation of the lens cover about microscope's objective lens barrel, a rotational adjustment of the lens cover about the barrel may interfere with the optical quality of the image received through the objective lens and drape lens cover. Thus there is a need for a microscope drape having a quantity and location of ocular pockets that can readily accommodate the various configurations of microscope ocular ports commonly used during a variety of surgical procedures.
Another disadvantage associated with prior art drapes arises where the lens cover of such drapes is mounted to the objective barrel such that the lens or window of the cover is located below the lower end of the barrel itself. Such drape lens covers thus result in an increased working distance (depth) of the microscope head during surgical procedures. This increased depth of the microscope results in longer working distances for the surgeon, thus requiring the surgeon to extend his or her arms during surgical procedures performed while viewing the surgical site through the microscope. An increased extension of the arms of the surgeon thus results in the surgeon having reduced surgical control, increased arm and hand fatigue and decreased hand and finger dexterity.
The location of the drape window below the objective lens barrel also results in the window being located towards the surgical site, thus increasing the likelihood of the occurrence of view obstructions on the window due to blood or tissue particles contacting the window itself. During a given surgical procedure, the microscope head may be repositioned many times in relation to the surgical site. Thus, a window location below the objective lens barrel increases the possibility of the surgeon contacting the window with his or her hands, with such contact again resulting in viewing obstructions occurring on the window. Thus, there is a need for a microscope drape having a lens cover with a window location that results in a reduced working distance (depth) of the microscope head during surgical procedures and a minimization of the occurrence of view obstructions on the window, due to blood or tissue particles contacting the window itself or due to an inadvertent touching of the window by medical staff.
Undesirable complications may also arise where the placement of the drape window below the lens barrel interferes with the surgical procedure itself. For example, the distal end of a surgeon's hand-held instruments may contact or collide with the window during use, thus resulting again in viewing obstructions occurring on the window. Such a collision of the instrument with the window may also interfere with the surgical procedure itself, thus slowing the procedure or adversely affecting the interaction between the instrument and the tissue contacted thereby within the surgical site. Thus, there is a need for a microscope drape having a lens cover with a window location that results in a reduced working distance (depth) of the microscope head during surgical procedures and a minimization of the occurrence surgical interference in the form of collisions between the window of the drape and the hand-held instruments of the surgeon.
In many surgical microscopes, the objective lens transmits light from a light source to the surgical site to illuminate the surgical site, with the objective lens also transmitting the image of the surgical site to the optical path of the microscope. Another disadvantage associated with prior art drapes thus arises where the lens cover results in a degraded optical quality of the viewed image due to a reflection of light from the microscope's light source off of the window of the drape lens and towards the objective lens of the microscope, resulting in glare. In an attempt to remedy this undesirable light reflection and glare, prior art drapes have utilized convex, concave or otherwise curved lens covers or windows to direct the light reflection away from the objective lens.
However, such lenses may cause a distortion of the view of the operative field, resulting in some surgeons discarding the lens or window of the drape lens cover during a given surgical procedure, thus compromising the sterile field around the microscope. With the drape window removed, bacteria or other contaminants present on the objective lens of the microscope itself may fall into the surgical site, thus increasing a likelihood for the occurrence of infection. A removal of the drape window also causes the objective lens of the surgical microscope itself to become exposed to blood and other fluids so that frequent cleaning may be required, thus increasing the potential to scratch or damage the objective lens, an expensive component of the surgical microscope. Finally, a curved drape lens or window results in an undesirable diffraction of a laser beam projected through the lens during image-guided surgeries. Thus, there is a need for an objective lens cover that maintains true sterility within the surgical field and minimizes the occurrence of glare, image distortion and laser diffraction during operative procedures.
Another problem that arises during certain surgical procedures such as power drilling on bone is that the lens can be obstructed or damaged by surgical debris. While a window covering the lens protects the expensive objective lens of the microscope from physical damage, the optical properties of the disposable lens cover itself can be degraded from view obstructions resulting from blood, bone, or tissue debris. Owing to their mass produced and disposable nature, lens covers packaged with surgical drape assemblies often have less than desirable optical qualities. The additional refraction of light rays caused by a disposable lens cover leads to unacceptable optical aberrations in precise procedures such as image guide measurements. It would thus be desirable in these situations for a surgeon to be able to temporarily remove the lens cover or to replace a defective or dirty lens cover with a clean sterile lens cover.
Accordingly, there remains a need for a true, sterile surgical microscope drape with a removable lens assembly. A removable lens assembly would permit a surgeon to easily replace a lens cover that is damaged or obstructed with debris with a clean and sterile one. The removable lens cover can also be temporarily removed to avoid optical aberrations in performing delicate surgical tasks. The present invention satisfies these needs.